Long chain aliphatic benzylphosphonic acids, esters and salts



United States Patent 3 363,032 LONG CHAIN ALIPHZATIC BENZYLPHOSPHONIC ACIDS, ESTERS AND SALTS Steven J. Fitch, St. Louis, Mo., assignor to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed June 11, 1964, Ser. No. 374,255 13 Claims. (Cl. 260-961) ABSTRACT OF THE DISCLOSURE Organo-phosphorus compounds useful as surface active agents, dry cleaning detergents in organic solvents and gasoline deicer additives are described having the formula 0 0X II/ wherein: R is an alkyl or alkenyl group containing from 6 to 20 carbon atoms and X is selected from the class consisting of hydrogen, lower alkyl radicals containing from 1 to 5 carbon atoms, and cations selected from the group consisting of alkali metal, ammonium and low molecular weight alkyl amines, alkylene amines and alkanol amines containing not more than 2 amine groups.

This invention relates to organic compounds of phosphorus and more particularly to long chain aliphatic benzylphosphonic acids as well as the esters and salts thereof.

An object of this invention is to provide new and useful organic compounds of phosphorus.

Another object of this invention is to provide long chain aliphatic benzylphosphonic acids as well as the erties and foam stability.

Other objects will be apparent from the following description.

This invention is directed to new and useful long chain aliphatic benzylphosphonic acids, as well as the esters and water-soluble salts thereof, said compounds having the general formula R OX wherein: R is an aliphati group containing from 6 to 20 carbon atoms and X is selected from the class consisting of hydrogen, lower alkyl radicals containing from '1 to 5 carbon atoms, and cations selected from the group consisting of alkali metal, ammonium, and amines.

For the symbol R representing aliphatic groups, such groups may be straight chain or branch chain and may be saturated or unsaturated, and preferably are alkyl groups and ethylenically unsaturated (especially alkenyl groups) and can also contain substituents, such as, hydroxyl, halides, i.e., fluoride, chloride, bromide and iodide, alkoxy groups, ester groups, ether groups, nitro groups, sulfonyl groups, amide groups, amine groups, carboxyl groups, nitroso groups and the like as long as they 3,363,032 Patented Jan. 9, 1968 "ice do not materially interfere with the hydrophobic nature of the aliphatic group. When the symbol X represents alkali metal, such may include lithium, sodium, potassium and the like, as well as mixtures of these, although sodium and potassium are preferred. When the symbol X represents amines, such are preferably low molecular weight amines, i.e., having a molecular weight below about 200, and more particularly the alkyl amines, alkylene amines and alkanol amines containing not more than 2 amine groups.

Especially preferred as surface active agents in aqueous systems are the alkylbenzylphosphonic acids and the water-soluble salts thereof having the general formula ll CHz-P wherein: R is an alkyl group containing from 8 to 18 carbon atoms and X is selected from the class consisting of hydrogen, and cations selected from the group consisting of alkali metal, ammonium, and amines. The preferred alkali metal salts and amine salts are those described hereinbefore for Formula 1.

The compounds of the invention can be prepared by various methods with the following method presented as being representative of their preparation.

In general, a long chain aliphatic benzyl halide (preferably chloride) and a tri-alkyl phosphite (preferably a tri-lower alkyl phosphite, such as methyl, ethyl, propyl, butyl or pentyl) can be reacted to form esters according to the reaction believed represented by the following equation:

OEt

+ EtCl OEt wherein: R represents the same groups as in the foregoing general Formula 1.

Usually temperatures in the range of from about C. to about 250 C. are preferred as well as an excess of phosphite of from about 20 to about 60 weight percent. Reaction times are usually several hours, i.e., from about 2 hours to about 15 hours.

The long chain aliphatic benylphosphonic acids can be prepared by the hydrolysis of the corresponding esters with a concentrated mineral acid. Generally, by refluxing the ester and a concentrated mineral acid, such as HCl or HBr, at reflux temperatures for a period of usually about 5 hours is all that is necessary for the hydrolysis.

The salts of the long chain aliphatic benyl phosphonic acids can be prepared by neutralization of the acids with a stoichiometric amount of a base or a salt of a volatile acid that contains essentially the desired cation. For example, to make a sodium salt, the long chain aliphatic benylphosphonic acid can be neutralized with a stoichiometric amount of a base containing the sodium cation, such as NaOH, Na CO and the like.

The following examples are presented to illustrate the invention with parts by weight being used in the examples unless otherwise indicated.

Example 1 Into a suitable reaction vessel are charged about 275 parts of pentadecylbenzylchloride and about 204 parts of triethyl phosphite. The temperature is raised to about C. for about 7 hours at which time the temperature is slowly raised to about C. When the evolution of ethyl chloride has essentially stopped (about 4 hours later), the reaction product is distilled in a molecular still at about 180-190 C. to yield di-ethyl pentadecylbenzylphosphonate.

Example 2 The ester of Example 1 is hydrolyzed with excess concentrated HCl for about 34 hours on a steam bath. The product usually forms in a gelatinous layer which can be recovered by decanting the aqueous layer and dissolving the product (residue) in ethanol and evaporating the ethanol. For purification purposes it is advantageous to redissolve the product in hot Water maintained at a high pH (about pH of 10) and acidifying the alkaline solution with an acid (5 N HCl) to precipitate the product, pentadecylbenzylphosphonic acid.

Example 3 Disodium pentadecylbenzylphosphonate is prepared by dissolving the free acid obtained as in Example 2 in hot water (about 70 C.) maintained at a high pH (about 11 or 12) with NaOH and evaporating the aqueous solution to dryness at about 140 C.

Example 4 Into a suitable reaction vessel are charged about 302 parts of dodecylbenzylchloride and about 165 parts of tri-ethyl phosphite. The temperature is raised to about 140 C. for about 10 hours at which time the temperature is slowly raised to about 160 C. When the evolution of ethyl chloride has essentially stopped (about 4 hours later) the reaction product is distilled in a molecular still at about 155-165 C. to yield diethyl dodecylbenzylphosphonate.

Example 5 The ester of Example 4 is hydrolyzed with excess concentrated HCl for about 30 hours on a steam bath. The product layer is recovered in substantially the same manner as in Example 2 to yield dodecylbenzylphosphonic acid.

Exampleo Dipotassium dodecylbenzylphosphonate is prepared by dissolving the free acid obtained as in Example 5 in hot water (about 70 C.) maintained at a high pH (about 11 or 12) with KOH and evaporating the aqueous solution to dryness at about 140 C.

Other long chain aliphatic benzy-lhalides which can be reacted with tri-lower alkyl phosphites according to the procedures as illustrated by the foregoing examples to form compounds of the instant invention include tetradecyl-, decyloctyland hexy-lbenzylchloride; hexadecenyl-, octadecenyl-, tetradecenyl-, dodecenyl-, decenylbenzylchloride; octadecadienylbenzylchloride and the like.

Other bases or salts of volatile acids which can be reacted With the free acids to produce salt compounds of the instant invention according to the procedures as illustrated by the foregoing examples include such inorganic alkali metal salts, oxides and hydroxides as NaNO Na O, Na CO KOH, K 0, K C KNO LiOH, LiNO Li C0 and the like, ammonium compounds such as (NH CO NH OH, and the like, and amines such as ethyl amine, diethyl amine, propyl amine, ethanol amine, triethanol amine, propylene diamine, propanol amine, 2-ethylhexyl amine, and the like.

The acid and Water-soluble salt compounds of the present invention are useful in minor amounts (usually from about 0.01% to about by weight) in aqueous solutions as surface tension reducing agents and the acid compounds exhibit the highly desirable features of being good Wetting agents as well as exhibiting good foam stability which is advantageous in such uses as hard surface cleansing compositions, toothpaste compositions, and the like.

The ester compounds of the present invention are useful in minor amounts (usually from about 0.005% to 5% 4 by weight) in gasoline as gasoline de-icer additives and are useful with many organic solvents such as perchloroethylene in amounts from about 05% to 10% by Weight as dry-cleaning surfactants.

What is claimed is: 1. A compound having the formula OOX B OX

OOH

CHri

R on

wherein: R is selected from the class consisting of alkyl and alkenyl radicals containing from 6 to 20 carbon atoms.

3. A long chain aliphatic benzylphosphonate ester compound having the formula R OR wherein R is selected from the class consisting of alkyl and alkenyl groups containing from 6 to 20 carbon atoms and R is a lower alkyl group containing from 1 to 5 carbon atoms.

4. A salt compound of a long chain aliphatic benzylphosphonic acid, said salt having the formula CHri wherein: R is selected from the class consisting of alkyl and alkenyl groups containing from 6 to 20 carbon atoms and X is a cation selected from the group consisting of alkali metal, ammonium and low molecular weight alkyl amines, alkylene amines and alkanol amines containing not more than 2 amine groups.'

5. An alkylbenzylphosphonic compound having the formula oHPi R ox

wherein: R is an alkyl group containing from 8 to 18 carbon atoms and X is selected from the class consisting of hydrogen and cations selected from the group consistmg of alkali metal, ammonium, and low molecular weight alkyl amines, alkylene amines and alkanol amines-coutammg not more than 2 amine groups.

6. Alkylbenzylphosphonic acid having the formula fi/OH CH2-P wherein: R is an alkyl group containing from 8 to 18 carbon atoms.

7. A salt compound of alkylbenzylphosphonic acid, said salt having the formula 8. Pentadecylbenzylphosphonic acid.

9. Diethyl pentadecylbenzylphosphonate. 10. Disodium pentadecylbenzylphosphonate. 11. Diethyl dodecylbenzylphosphonate.

12. Dodecylbenzylphosphonic acid.

13. Disodium dodecylbenzylphosphonate.

References Cited UNITED STATES PATENTS 2,594,454 4/1952 Kosolapoff 260-961XR 2,765,279 10/1956 Nusslein 260500 CHARLES B. PARKER, Primary Examiner.

15 A. H. SUTTO, Assistant Examiner. 

